Field of the Invention
The present disclosure relates to a VCM (Voice Coil Motor), and more particularly to a voice coil motor enabling to bi-directionally drive a rotor using a small current by floating the rotor from a base.
Description of Related Art
Recently, a mobile phone embedded with a super small digital camera has been developed. A conventional super small digital camera used on a mobile phone has suffered from a disadvantage of disablement to adjust a gap between a lens and an image sensor changing an outside light to a digital image or a digital video (moving image). However, recently, a lens driving device such as a voice coil motor capable of adjusting a gap between an image sensor and a lens has been developed to obtain a digital image or a digital video more advanced than that of a conventional super small digital camera.
Generally, a VCM (Voice Coil Motor) is mounted therein with a lens, where a bobbin arranged on a base is vertically moved from the base to adjust a gap between an image sensor arranged at a rear surface of the base and a lens of the camera. The bobbin of the VCM is coupled with a leaf spring to be always brought into contact with the base by elastic force of the leaf spring when the VCM is not operated. That is, the conventional VCM is driven only to one direction relative to the base.
Because the conventional VCM is driven only to one direction, the VCM disadvantageously needs a driving force greater than a self-weight of the bobbin and the elastic force of the leaf spring to drive the VCM, causing a greater increase in power consumption of the VCM. The conventional VCM further suffers from a disadvantage in that, because it needs a driving force greater than a self-weight of the bobbin and the elastic force of the leaf spring, size of coil wound on the bobbin or the leaf spring increases to increase an entire size of the VCM.